PMW Feature

Ok, so yesterday my http://www.zalman.co.kr/ENG/product/Product_Read.asp?Id... broke off while i was at school. The bracket snapped in 2 for some odd reason and it killed my sound card on impact. The good part is that the local shop i had got the card from agreed to change it (it didn't look like it got hit), but i still had to buy a new cpu cooler, so i got a http://www.zalman.co.kr/ENG/product/Product_Read.asp?Id... , which i believe is exactly the same but more silent.

So anyway, this new cooler has something called PWM (pulse width modulation). I seem to understand how this thing works, but what exactly are its benefits? My old cpu fan had something which was called Fan Mate (I didn't use it as i like keeping my fans on 100%), but i never fiddled with PWM before.

Im running an Asus Crosshair mobo, so im not sure it has support for it.

Thanks for any answers.